Microstructural evolution and age hardening in aluminium alloys: Atom probe field-ion microscopy and transmission electron microscopy studies

This paper examines the microstructural evolution in selected aluminium all oys based on commercial age hardenable 2000, 6000, and 7000 series alloys. Atom probe field-ion microscopy and transmission electron microscopy have b een used to examine the effects of microalloying and the origins of hardeni ng. The combined application of these techniques is particularly important in the study of nanoscale precipitation processes. It is shown that the nat ure and kinetics of the precipitation process depend on the solute-solute i nteractions that produce solute clusters. The solute clusters precede the f ormation of GP zones or precipitation, and have a defining role on the natu re and kinetics of the subsequent precipitation processes. Moreover, intera ctions between solute clustering and dislocations can have a significant ha rdening effect, the origins of which seem to be distinctly different from t he conventional notion of precipitation hardening. (C) Elsevier Science Inc ., 2000. All rights reserved.